1. Field of the Invention
The present invention relates to an injection molding system that includes one or more injection molding machines, each equipped with a controller that operates in accordance with a computer program.
2. Description of the Related Art
In general, injection molding machines are equipped with a controller for performing various kinds of control, and a computer program (hereinafter simply referred to as a "program") for performing the various kinds of control is stored in a memory provided in the controller.
Conventionally, such a program is stored in the memory of the controller in the course of manufacture of the controller or the injection molding machine at a manufacturer's plant. That is, a P-ROM in which a program has been written in advance is installed in the controller in the course of manufacture of the controller, or a program is written in a P-ROM which has been built into the controller, through the use of a program developing apparatus.
Since the amount of program data has increased in recent years due to enhanced performance and an increased number of functions of injection molding machines, the program data has been become difficult to store in a P-ROM, whose storage capacity is limited. In order to cope with this problem, there has been employed a technique in which a hard-disk drive is built into a controller, and a control program and various kinds of data are stored in the hard-disk drive (see Japanese Patent Application Laid-Open (kokai) Nos. 3(1991)-5123 and 7(1995)-266395).
However, the technique in which a hard-disk drive is built into a controller has the following problems.
First, in many cases, controllers mounted on injection molding machines are placed under severe conditions such as exposure to vibration (shock), high temperature, and dust. Therefore, there exists a fear that a precision hard-disk drive will cause error or failure, or that a program stored in the hard-disk drive will become erased or damaged. Therefore, such a technique is disadvantageous from the viewpoint of reliability and safety.
Second, a hard-disk drive--which is an expensive device--must be incorporated into the controller, resulting in an increase in the size and cost of the controller.
Third, every time a program is replaced with an upgraded version, an installation operation must be performed through use of a CD-ROM or the like.